#include<bits/stdc++.h>

using namespace std;

//输出棋盘 基本思想
int main() {
    int h, w, x, y;
    int n = 40;
    for (x = 1; x <= n; x++) {
        for (y = 1; y <= n; y++) {
            if ((x + y) % 2 == 0)
                cout << "#";
            else
                cout << ".";
        }
        cout << endl;
    }

    return 0;
}
